Encyclopedia of Health and Medicine

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smoking and health There are no health benefits
and numerous health risks from cigarette smoking.
In the 1940s few people, including doctors, recognized
the magnitude of health risks associated with
cigarette smoking. But 20 years later cigarette
smoking was a known and publicly identified risk
factor for numerous health conditions and the primary
cause of HEART disease and LUNG CANCER. In the
1965 cigarette smoking in the United States peaked
with about 45 percent of American adults being
smokers; by the early 2000s, only 23 percent of
American adults smoked. However, that 23 percent
represents 48 million people who have significantly
increased risk for CARDIOVASCULAR DISEASE (CVD),
chronic lung disease, and cancer. Cigarette smoking
remains the leading cause of preventable disease in
the United States.
PACK YEARS AND DISEASE RISK
One method of representing the amount of cigarette
smoke exposure an individual has had is
the “pack year.” This calculation expresses the
number of packs of cigarettes a person smokes
each day times the number of years the person
has smoked. A person who has smoked for 10
pack years may have smoked half a pack a day
for 20 years, one pack a day for 10 years, or two
packs a day for five years. The higher the number
of pack years, the greater exposure and more significant
the risk of pulmonary and cardiovascular
disease.
How Smoking Affects the Body and Health
Cigarette smoking affects every cell in the body
beginning within seconds of the first inhalation
from a cigarette. NICOTINE contracts BLOOD vessels,
increases HEART RATE, raises BLOOD PRESSURE, and
activates neurotransmitters in the BRAIN that result
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in CENTRAL NERVOUS SYSTEM stimulation to produce
a combined sense of exhilaration and alertness.
With each inhalation of cigarette smoke, tar
makes its way to the delicate alveoli deep within
the LUNGS, clogging them and preventing them
from exchanging oxygen. Other chemicals in the
smoke irritate the bronchi, causing an increase in
mucus production and narrowing of the bronchial
openings. Carbon monoxide beats out oxygen to
bind with HEMOGLOBIN in the red blood cells (erythrocytes),
cutting by up to 60 percent the
amount of oxygen each breath carries into the
blood circulation. The combined effects of these
actions and the chemicals that enter the bloodstream
affect cellular METABOLISM in countless
ways. Dozens of these chemicals are carcinogenic;
they cause cells within the body to develop into
cancers. Some of the effects linger for hours after
the cigarette and compound with further smoking.
Cigarette smoking and CVD The leading health
consequence of cigarette smoking is CVD.
Repeated exposure to nicotine causes permanent
changes in the cells that form the lining of the
arteries, making the arteries vulnerable to ATHERO-
SCLEROTIC PLAQUE deposits and, over time, ATHERO-
SCLEROSIS, CORONARY ARTERY DISEASE (CAD), and
PERIPHERAL VASCULAR DISEASE (PVD). Persistent nicotine
exposure also causes the arteries to stiffen and
lose FLEXIBILITY. These changes lead to HYPERTENSION
(high blood pressure) and increased risk for HEART
ATTACK and STROKE. The strain on the heart can
eventually cause HEART FAILURE.
Cigarette smoking and cancer The primary
form of cancer associated with cigarette smoking is
lung cancer. However, cigarette smoking increases
the risk for various forms of cancer, including oral
cancer, laryngeal cancer, ESOPHAGEAL CANCER, PAN-
CREATIC CANCER, BLADDER CANCER, PROSTATE CANCER,